1. Field of the Invention
The present invention relates to a reinforced absorbable patch for the replacement of a portion of bladder wall following partial bladder removal (cystectomy).
2. Description of the Related Art
As is known, when a portion of the bladder of a patient is affected by a serious disease, such as partial neoplasm or bilharzia (schistosomiasis), this portion of bladder must be removed to prevent the disease spreading to the entire bladder. The removal of this portion of bladder wall creates a hole in the bladder which is closed by using a patch which is sutured in the perimeter of the bladder wall which defines this hole.
Patches are generally devices made up of tissue deriving from the intestine of the patient turned inside out or from synthetic textiles, for example silicone or textile in polypropylene as described in the patent applications WO 2007/039160 and PCT/EP2008/006352 in the name of the Applicant, rendered more biocompatible by means of covering with a layer of pyrolytic turbostratic carbon, or of fatty acids of the omega-3 family.
The purpose of synthetic patches is to replace temporarily the part of bladder removed while awaiting regeneration of the tissues of the bladder around the hole and therefore they have to be removed at a later time by means of subsequent further surgery endoscopically on a day hospital basis. This operation however is not always easy to carry out, in particular on elderly patients.
Moreover bladder patches have to possess a combination of properties which cannot always be achieved by known synthetic or natural patches: such rigidity as to allow the bladder to retain its shape at least until its removal, and at the same time sufficient elasticity and flexibility as to ensure the correct deformation of the patch during the physiological functioning of the treated bladder.
Additionally the bladder patch has to exhibit both chemical resistance and impermeability to urine at least for the entire period from the implanting up to its removable, or absorption. Moreover the patch must not collapse under the weight of the growing tissues, a phenomenon which is instead typical of low-thickness patches, nor exhibit adherences to the surrounding fibrous capsule.
An alternative solution to the aforementioned patches which are not absorbable is represented by the use of three-dimensional matrices, generally in bioabsorbable material, which act as substrate to be populated with stem cells of the diseased organ grown in vitro in order to obtain a piece of biological tissue which will then be implanted in place of the portion of diseased tissue. This procedure allows excellent results to be obtained in terms of compatibility and mechanical performances but is very complex, with long performance times, and costly.
In order to overcome the aforementioned disadvantages the Applicant has developed an absorbable patch in PGA fibres and reinforced with strips of PGA textile able to overcome the limits of the prior art stated above. See patent application WO2011/064110. However further tests performed by the Applicant have shown that this patch very often tends to collapse towards the interior of the bladder, very probably due to the weight of the neotissue growing after the implant: this collapse leads to uneven growth of the neotissue creating adherences in the point of implant and adherence to the fibrous capsule.
Moreover this patch, being made throughout with fibres of PGA homopolymer, has an absorption time of the order of 30 days, similar to the time of growth of bladder neotissue: this entails a decline in the mechanical properties during this period of absorption which consequently leads to the collapse of said patch under the weight of the new tissue growing, given the decreased rigidity in said space of time.
US 2005/0113938 describes a biocompatible implant for the reconstruction of tissues, different from the bladder tissue, formed by a foam made up, among others, of PGA/PLA which is reinforced with textile elements or meshes, formed, among others, by fibres of PGA/PLA.
This implant is however poorly suitable for the replacement of a bladder wall in light of the high porosity, both of the foam and of the reinforcement elements, which, although on the one hand ensures the populating of the implant by the growing neotissue, on the other hand determines an undesirable leakage of urine from the bladder during the growth of the autologous neotissue.
Moreover both the solutions of the aforementioned prior art have little possibility of adapting and conforming, during surgery, to the portion of bladder removed in the case wherein the latter has a curvature, albeit slight.